Module ca.on.oicr.gsi.shesmu

Package ca.on.oicr.gsi.shesmu.plugin.cache

Class LabelledKeyValueCache<K,L,V>

java.lang.Object

ca.on.oicr.gsi.shesmu.plugin.cache.LabelledKeyValueCache<K,L,V>

Type Parameters:

K - the keys to use to lookup data in the cache

L - the "label" associated with a key; this allows a key's lifecycle to be different from its data's

V - the values retrievable from the cache based on state and key

All Implemented Interfaces:

Owner, Iterable<Map.Entry<L,Record<V>>>

public abstract class LabelledKeyValueCache<K,L,V>
extends Object
implements Owner, Iterable<Map.Entry<L,Record<V>>>

Store data that must be generated/fetched remotely and cache the results for a set period of time.

Field Summary

Fields inherited from interface ca.on.oicr.gsi.shesmu.plugin.cache.Owner

CPU_TIME

Constructor Summary

Constructors

Constructor	Description
LabelledKeyValueCache(String name, int ttl, RecordFactory<V> recordCtor)	Create a new cache

Method Summary

Modifier and Type	Method	Description
static Stream<? extends LabelledKeyValueCache<?,?,?>>	caches()
protected abstract V	fetch(K key, L label, Instant lastUpdated)	Fetch an item from the remote service (or generate it)
final V	get(K key)	Get an item from cache
final V	getStale(K key)	Get an item from cache without updating it
final void	invalidate(K key)
void	invalidateAll()
final Iterator<Map.Entry<L,Record<V>>>	iterator()
protected abstract L	label(K key)	The fixed label associated with the specified key
final String	name()	The name of the cache for use in monitoring
final long	ttl()	The time-to-live for a record in cache
final void	ttl(int ttl)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Details

LabelledKeyValueCache

public LabelledKeyValueCache(String name,
 int ttl,
 RecordFactory<V> recordCtor)

Create a new cache

Parameters:

name - the name, as presented to Prometheus

ttl - the number of minutes an item will remain in cache

Method Details

caches

public static Stream<? extends LabelledKeyValueCache<?,?,?>> caches()

fetch

protected abstract V fetch(K key,
 L label,
 Instant lastUpdated)
                    throws Exception

Fetch an item from the remote service (or generate it)

Parameters:

key - the item to be requested

lastUpdated - the last time the item was successfully fetched

Returns:

the cached value

Throws:

Exception - if an error occurs, the previous value will be retained

get

public final V get(K key)

Get an item from cache

Parameters:

key - the key to use

Returns:

the value, if it was possible to fetch; the value may be stale if the remote end-point is in an error state

getStale

public final V getStale(K key)

Get an item from cache without updating it

Parameters:

key - the key to use

Returns:

the last value that was fetched

invalidate

public final void invalidate(K key)

invalidateAll

public void invalidateAll()

iterator

public final Iterator<Map.Entry<L,Record<V>>> iterator()

Specified by:

iterator in interface Iterable<K>

label

protected abstract L label(K key)

The fixed label associated with the specified key

name

public final String name()

Description copied from interface: Owner

The name of the cache for use in monitoring

Specified by:

name in interface Owner

ttl

public final long ttl()

Description copied from interface: Owner

The time-to-live for a record in cache

Specified by:

ttl in interface Owner

ttl

public final void ttl(int ttl)